Mumbai University Previous year question papers
IV Sem ETC-Examination Dec 2008
Principles of Communication
N.S. (1) Question No.1 is compulsory.
(2) Attempt any four questions out of remaining six questions.
(3) Assume suitable data if required.
1. Answer the following: (Any four)
(a)’ Explain why FM is more immune to noise.
(b) Write a note on TOM.
(c) Explain double spotting in radio receivers.
(d) With the help of diagram explain quantization.
(e) Explain the need of modulation and classify the different types of modulation techniques.
2. (a) S1ate advantages of SSB over DSB. Explain anyone method to genemte SSB. 10
(b) State advantages and disadvantages of digital transmission. With neat block diagram explain the operation of single channel, simplex PCM transmission system.
3. (a) State and prove sampling theorem. 10
(b) Draw a neat block diagram of super-heterodyne radio receiver and explain the function of each block with waveforms.
4. (a) Draw the block diagram of linear delta modulator with suitable waveforms and explain its working. .
(b) Define FM and derive equation of FM wave. 10
5. (a) Explain generation and demodulation of PWM signal with the help of.suitable diagrams. 10
(b) Explain noise figure measurement using ‘diode noise generator’ method. 10
6. (a) Draw the schematic diagram of high – power AM DSBFC modulator and explain the operati0n.
(b) Explain the following with reference to radio receivers :-
(i) Sensitivity (iii) Fidelity
(ii) Selectivity (iv) Dyncrmic range
7. (a) Draw the following data waveforms for the bit stream 11001010.
(i) Unipolar NRZ (iv) Bipolar RZ
(ii) Bipolar NRZ (v) Bipolar RZ-AMI
(iii) Unipolar RZ
(b) For an angle modulated carrier Vc = 6 cos(2rc11OMHz t) with 75 kHz frequency deviation due to the information signal and a single frequency interfering signal Vn = 0.3 cos (2rc109;985 MHz t), determine –
(i) Frequency of the demodulated interference signal
(ii) Peak phase and frequency deviations due to the interfering signal.
(iii) Voltage signal-to-noise ratio at the output of the demodulator.